Apparatus and method for detecting ice

Abstract

An apparatus for detecting ice includes a heat flow sensor which senses the rate of flow of heat through a member. At the same time, the temperature differential across the member is determined. Based on the temperature differential, it is possible to calculate a theoretical heat flow rate based on the assumption that there is no ice on the member. If ice is present on the surface of the member, the actual heat flow rate will be significantly less than the calculated or theoretical heat flow rate. It is contemplated that the apparatus and method of this invention will be particularly useful in conjunction with the detecting of the presence of ice on a wing of an aircraft.

Having described the invention, the following is claimed: 
     
       1. An apparatus for detecting the presence of ice on a surface of a member, said apparatus comprising means for sensing the rate of heat flow through a portion of the member, means for determining the actual temperature adjacent opposite sides of the member, means for calculating the rate of heat flow through the portion of the member as a function of the temperatures adjacent opposite sides of the member and based on the assumption that the surface of the member is free of ice, and means for comparing the calculated rate of heat flow to the sensed rate of heat flow to determine if ice is present on the surface of the member. 
     
     
       2. An apparatus as set forth in claim 1 further including means for securing said means for sensing the rate of heat flow through the member to the surface of the member. 
     
     
       3. An apparatus as set forth in claim 1 wherein said means for determining the temperature adjacent to opposite sides of the member includes a temperature sensor and a body of heat insulating material disposed between said temperature sensor and the surface of the member. 
     
     
       4. An apparatus as set forth in claim 1 wherein said means for determining the temperature adjacent to opposite sides of the member includes first temperature sensor means for sensing the temperature adjacent to a first side of the member and second temperature sensor means for sensing the temperature adjacent to a second side of the member opposite from the first side of the member. 
     
     
       5. An apparatus as set forth in claim 1 wherein the member includes a first side upon which includes the surface upon which the presence of ice is to be detected and a second side opposite from the first side, said means for determining the temperature adjacent to opposite sides of the member includes first sensor means for sensing the temperature adjacent to the first side of the member and second sensor means for determining the temperature adjacent to the second side of the member, said means for sensing the rate of heat flow through the member being disposed between the first and second sides of the member. 
     
     
       6. An apparatus as set forth in claim 1 further including means for securing the member to a surface upon which ice may form contemporaneously with the formation of ice on the surface of the member. 
     
     
       7. An apparatus for detecting the presence of ice on the surface of an aircraft wing which contains a fuel tank, said apparatus comprising heat flow sensor means for sensing the rate of flow of heat being conducted between a portion of the fuel tank and a portion of the surface of the aircraft wing, first temperature sensor means for sensing the temperature of a portion of the fuel in the fuel tank, second temperature sensor means for sensing the temperature adjacent to the surface of the aircraft wing, means for calculating a theoretical heat flow rate between the fuel tank and the surface of the aircraft wing as a function of the temperatures sensed by said first and second temperature sensor means, and means for comparing the calculated theoretical heat flow rate between the fuel tank and the surface of the aircraft wing to the sensed rate of flow of heat to determine if ice is present on the surface of the aircraft wing. 
     
     
       8. An apparatus for detecting the presence of ice on a wing of an aircraft, said apparatus comprising first heat flow sensor means mounted on an upper side surface of the aircraft wing for sensing the rate of heat flow through a portion of the upper surface of the aircraft wing, second heat flow sensor means mounted on a lower surface of the aircraft wing for sensing the rate of heat flow through a portion of the lower surface of the aircraft wing, and means for comparing the rates of flow of heat through the upper and lower surfaces of the aircraft wing to determine if ice is present on the aircraft wing. 
     
     
       9. A method of detecting the presence of ice on a surface of an aircraft wing, said method comprising the steps of sensing the rate of heat flow through a portion of the surface of the aircraft wing, determining the temperature within a portion of the aircraft wing, determining the temperature of the air outside the aircraft wing, calculating a rate of heat flow through the portion of the surface of the aircraft wing as a function of the temperature inside the aircraft wing and as a function of the temperature of the air outside the aircraft wing and based on the assumption that the surface of the aircraft wing is free of ice, and comparing the calculated rate of heat flow to the sensed rate of heat flow to determine if ice is present on the surface of the aircraft wing. 
     
     
       10. A method of detecting the presence of ice on the wing of an aircraft, said method comprising the steps of sensing the rate of heat flow through a portion of an upper surface of the aircraft wing, sensing the rate of heat flow through a portion of a lower surface of the aircraft wing, and comparing the rates of flow of heat through the portions of upper and lower surfaces of the aircraft wing to determine if ice is present on the aircraft wing. 
     
     
       11. A method for detecting the presence of ice on a surface of an aircraft wing, said method comprising the steps of determining the temperature adjacent to a first side of a member, said first side of the member being protected from exposure to the air around the aircraft wing, determining the temperature adjacent to a second side of the member, said second side of the member being exposed to the air around the aircraft wing, sensing the rate of heat flow between portions of the first and second sides of the member, calculating a rate of heat flow through the portion of the second side of the member as a function of the temperatures adjacent to the first and second sides of the member and based on the assumption that the second side of the member is free of ice, and comparing the calculated rate of heat flow to the sensed rate of heat flow to determine if ice is present on the second side of the member and the surface of the aircraft wing. 
     
     
       12. A method as set forth in claim 11 wherein the member forms part of the aircraft wing. 
     
     
       13. A method as set forth in claim 11 wherein the member is formed separately from and is secured to the aircraft wing.